In order to prepare rolls of cooked meat such as for example joints of ham, these are disposed before cooking in alveoli in trays that are stacked or on staged frames. A heat treatment vessel of the prior art consists of a hermetic chamber provided with a cover. An example of a method of preparing rolls of food products is as follows:
the cover of the empty vessel is opened,
a stack of trays or a staged frame filled with rolls of raw food products is deposited in the vessel,
the cover of the vessel is closed,
the vessel is filled with hot water until the end of cooking,
the vessel is emptied,
the vessel is filled with cold water until the end of cooling,
the vessel is emptied,
the cover is opened,
the stack of trays or the staged frame is removed from the vessel and transferred to the food product discharge area.
Such a heat treatment vessel can through its configuration pose certain problems with respect to local health standards since the food products enter and leave the vessel through the same opening.